Punjab Islanding Scheme - Northern Regional Power Committee

ANEXURE III
TECHNICAL SPECIFICATION OF UFRs :
The broad technical specification of islanding relays for the proposed load
shedding scheme is as under:
a. Rating:
The rated auxiliary voltage : 220V + 5% (D.C).,
The rated system frequency: 50 Hz
Nominal voltage : 110V (A.C). Phase-Phase from P.T’s.
b. Operating frequency range : 45 to 55 Hz in steps 0.1 Hz with accuracy + 10 mHz.
c. Under Voltage block at 40% of P.T. Voltage.
d. Recovery function: Frequency difference from set value 0.1 to 2.0 Hz. Resetting
time – 15 Sec. to 15 minutes. Accuracy + 1%.
e. The relays should be immune to harmonics & transients.
f. It should have feature to self monitor. It should also be possible to monitor the
relay from remote.
g. The relay should have at least 4 levels of settable under frequency levels.
h. The relay should have at least 2 levels of settable over frequency levels.
i. The relay should have three load shedding stages for df/dt function and each
stage should have setting range of 0.1 to 3 Hz (incremental in steps of 0.1
Hz/Sec).
j. The each output contact of relays shall be configurable based on frequency
whether over and under frequency values.
k. The relay shall be IEC 61850 Compliant and shall communicate with SCADA
system located at a remote location through owner communication network
through 2mbps Ethernet port.
l. The relay shall have at least four (4) voltage inputs where PT can be
connected directly without any additional interfacing equipment.
m. The relay shall have at least 12 status input and 6 trip output contacts to trip
at least 6 feeders & monitor Main & Tie CBs of these 6 feeders. The output
contacts shall be wired to self reset heavy duty trip relays to trip Main & Tie
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